title: Postpartum changes in maternal and infant erythrocyte fatty acids are likely to be driven by restoring insulin sensitivity and DHA status.
abstract: BACKGROUND
  Perinatal changes in maternal glucose and lipid fluxes and de novo lipogenesis (DNL) are driven by hormones and nutrients. Docosahexaenoic acid (DHA) reduces, whereas insulin augments, nuclear abundance of sterol-regulatory-element-binding-protein-1 (SREBP-1), which promotes DNL, stearoyl-CoA-desaturase (SCD, also Δ9-desaturase), fatty acid-(FA)-elongation (Elovl) and FA-desaturation (FADS). Decreasing maternal insulin sensitivity with advancing gestation and compensatory hyperinsulinemia cause augmented postprandial glucose levels, adipose tissue lipolysis and hepatic glucose- and VLDL-production. Hepatic VLDL is composed of dietary, body store and DNL derived FA. Decreasing insulin sensitivity increases the contribution of FA from hepatic-DNL in VLDL-triacylglycerols, and consequently saturated-FA and monounsaturated-FA (MUFA) in maternal serum lipids increase during pregnancy. Although other authors described changes in maternal serum and RBC essential-FA (EFA) after delivery, none went into detail about the changes in non-EFA and the mechanisms behind -and/or functions of- the observed changes.
  
  
  OBJECTIVE
  Postpartum FA-changes result from changing enzymatic activities that are influenced by the changing hormonal milieu after delivery and DHA-status.
  
  
  METHODS
  We studied FA-profiles and FA-ratios (as indices for enzymatic activities) of maternal and infant RBC at delivery and after 3 months exclusive breastfeeding in three populations with increasing freshwater-fish intakes. DNL-, SCD- and FADS2-activities decreased after delivery. Elongation-6 (Elovl-6)- and FADS1-activities increased. The most pronounced postpartum changes for mothers were increases in 18:0, linoleic (LA), arachidonic acid (AA) and decreases in 16:0, 18:1ω9 and DHA; and for infants increases in 18:1ω9, 22:5ω3, LA and decreases in 16:0 and AA. Changes were in line with the literature.
  
  
  CONCLUSIONS
  Postpartum increases in 18:0, and decreases in 16:0 and 18:1ω9, might derive from reduced insulin-promoted DNL-activity, with more reduced SCD- than Elovl-activity that leaves more 16:0 to be converted to 18:0 (Elovl-activity) than to MUFA (SCD-activity). Postpartum changes in ΣDNL, saturated-FA and MUFA related negatively to RBC-DHA. This concurs with suppression of both SCD- and Elovl-6 activities by DHA, through its influence on SREBP. Infant MUFA and LA increased at expense of their mothers. Sustained transport might be important for myelination (MUFA) and skin barrier development (LA). Maternal postpartum decreases in FADS2-, and apparent increases in FADS1-activity, together with increases in LA, AA, and 22:5ω3, but decrease in DHA, confirm that FADS2 is rate limiting in EFA-desaturation. Maternal LA and AA increases might be the result of rerouting from transplacental transfer to the incorporation into milk lipids and discontinued placental AA-utilization.
  
  
  CONCLUSIONS
  Perinatal changes in maternal and infant FA status may be strongly driven by changing insulin sensitivity and DHA status.
authors.affiliation: Laboratory Medicine, University Medical Center Groningen (UMCG), The Netherlands. remkokuipers@hotmail.com
authors.forename: Remko S
authors.initials: RS
authors.lastname: Kuipers
authors.forename: Martine F
authors.initials: MF
authors.lastname: Luxwolda
authors.forename: Wicklif S
authors.initials: WS
authors.lastname: Sango
authors.forename: Gideon
authors.initials: G
authors.lastname: Kwesigabo
authors.forename: Francien V
authors.initials: FV
authors.lastname: Velzing-Aarts
authors.forename: D A Janneke
authors.initials: DA
authors.lastname: Dijck-Brouwer
authors.forename: Frits A J
authors.initials: FA
authors.lastname: Muskiet
mesh_terms: D000090943:Delta-5 Fatty Acid Desaturase; D004281:Docosahexaenoic Acids / Q000097:blood*; D004912:Erythrocytes / Q000378:metabolism*; D005227:Fatty Acids / Q000097:blood*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007333:Insulin Resistance; D049590:Postpartum Period; D011247:Pregnancy
chemical_list: D000090943:Delta-5 Fatty Acid Desaturase; D005227:Fatty Acids; D004281:Docosahexaenoic Acids; C000716847:FADS1 protein, human